Tracking control device



Sept. 2, 1947. E. w; CHAFE E 2,426,597

I TRACKING CONTROL DEVICE Original Filed June 3. 19:58

SLIP connzcvwu 6| I07 EL. HAND- WHEEL 53 TIAL COMPUTER sup ONNECTION INVENTOR E. W. CH AFE E Patented Sept. 2, 1947 Original application June 3, 1938, Serial No. 211,550. Divided and this application April 2, 1943, Serial No. 481,637

Claims.

This invention relates to a tracking control device of the type employed in fire control systems for controlling the orientation of an object such as a gun or an optical sighting device. This application constitutes a division of copending application Serial No. 211,550, entitled Fire control system for aircraft guns, filed June 3, 1938, in the name of Earl W. Chafee which issued Sept. 25, 1945, as Patent No. 2,385,348.

The primary object of the invention is to provide apparatus whereby a fire control operator may easily and accurately control the orientation either of a gun or of an optical sighting device, such as a telescope, said apparatus including means for introducing into an associated computing mechanism data corresponding to the angular rate of motion of said gun or sight.

Other objects and advantages will become apparent from the specification taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated.

The single drawing is a schematic representation of the tracking control device of the present invention. In the drawing arrows are employed to indicate the direction of flow of information or control influence.

The tracking control device of the present invention is illustrated in the drawing as employed in a fire control system of the disturbed sight type. In this type of fire control system, the optical system which defines a line of sight to the target is carried on or, at least, driven synchronously with the gun. The computer of such a system is adapted to compute the lead angle between the gun orientation and the line of sight required for effective gunfire, and to automatically offset the optical line of sight With respect to the gun by an amount corresponding to this computed angle. In operation, the operator through his controls directly controls the orientation of the gun, thereby indirectly controlling the orientation of the optical line of sight, in such a manner as to maintain the optical line of sight on the target. In this Way the orientation of the gun is automatically offset from the line of sight to the target by the lead angle required to effect a hit.

"As more fully explained in the above-mentioned copending application Serial No. 211,550, in order to compute the required lead angle in such a system there'must be introduced into the computer, among other things, data corresponding to gun orientation in elevation and azimuth and the gun angular rate, also in elevation and azimuth.

It is the purpose of the apparatus of the present invention to enablethe operator to control the orientation of the gun, and, at the same time, set this required data into the computer.

Referring now to the drawing which shows diagrammatically the tracking control arrangement for a gun, the main control lever for operating the sight is a universally pivoted handle I, the angular motion of which may be identical with the movements of the gun. Motion thereof is transmitted in azimuth and elevation components, the former being transmitted by the rocking of the handle into and out of the plane of the paper which rotates displacement shaft 2 through a gear sector 3 and 3', which shaft runs to gun I00 to control its azimuth orientation. Rocking of lever I in the plane of the paper moves up and down the rack bar 4 to rotate pinion 5, shaft 5', and displacement shaft 6, the latter controlling the elevation of the gun.

Gun I00 is supported by mount IOI for rotation in elevation about horizontal trunnions I02, this rotation being effected from displacementshaft 6 which actuates the gear segment I04 carried by 5 the gun through gear I03. Mount IN is rotated in azimuth about a vertical axis from displacement shaft 2 by means of gear I06 meshing with the larger gear I05 integral with the mount. Gun azimuth (Ag) is transmitted to the computer I09 as a proportional rotation of shaft I01 which is actuated from shaft 2 through appropriate shafting and gearing. Similarly, gun elevation is transmitted to the computer I09 as a proportional rotation of shaft I08 which is driven from shaft 6. Obviously, if desired or necessary, a suitable follow-up system or torque amplifier could be inserted between shafts 2, 6 and the gun to provide a power drive.

The control handle I thus enables the operator to directly control the gun positions in azimuth and elevation. In addition, there is provided means for setting in through variable speed drives continuous azimuth and elevation movements at adjustable rates. This is accomplished by means of two variable speed drives 48 and 43', the driving discs of which are continuously driven from constant speed motor 50. The elevation variable speed drive 48 is shown as adjusted from the elevation rate handwheel 5| which turns an input arm of an equating differential 52. The output arm of said differential is connected through gearing 53 to shaft 54 which radially positions the ball carriage 55 of variable speed drive 48 throughbevel gearing 56 and rack and pinion- 5?. The output cylinder 58 of said variable speed drive actuates rate shaft [l which then drives shaft 6 through worm drive 59 which has a slip friction connection 65 with shaft 6. Shaft I II] also actuates a second input arm of differential 52 through gearing 6 I The mechanism is so arranged that the torque required to drive shaft 54 against the friction imposed by friction brake 62 and by the ball carriage 55 is less than the torque required to turn shaft III) against the load on shaft 6 and the friction imposed by the cylinder 58. Therefore, rotation of the elevation rate handwheel by the operator will drive through differential 52 to cause a displacement of shaft 54. Displacement of shaft 54 will correspondingly remove ball' carriage 55 from its neutral position thereby causing the cylinder 58 to be driven at a corresponding rate from the constant speed motor 50. The rate of rotation of cylinder 58 will be subtracted in differential 52 from the rate of rotation of handwheel and the difference, if any, willactuate shaft 54 and ball carriage 55. It is ap-' parent that ball carriage 55 may be displaced by rotation of the handwheel until the rate of rotation of cylinder 58 and shaft III} is equal to that of rate handwheel 5!. Since shaft III] also causes a corresponding rotation of shaft 6 and gun I00 in elevation, the gun will thereby be ele-' -vated at a rate proportional to that of the elevation rate handwheel.

Accordingly, the operator rotates the handwheel at whatever speed is required to produce the desired rate of rotation of the gun I90 and then lets go. When helets go, owing to the load imposed on shaft 54 by friction brake 62, shaft 54 remains stationary and the rotation of shaft III] will be transmitted through worm-gear 59' and friction connection 60 to shaft 6, and also through differential 52 to therate handwheel 5!, which is now free and will therefore continue to rotate at the imparted rate. Inthis mannerany change of speed imparted to the rate handwheelby the operator will be automatically kept up, and moreover, will cause rotation of the gun at a proportional rate. Thus, the operator may cause the gun to be continuously elevated at any desired rate.

As is well known, the linear displacement of ball carriage 55 from its neutral position is proportional to the rate of rotation of cylinder 58 and-therefore, is proportional to the rate of rotation of gun Hill. The angular displacement of shaft 54, corresponding to the displacement of. ball carriage 55-from its neutral position, istherefore proportional to'the gun=elevation rate (Egr). Shaft 54 is therefore connected into computer I09 to provide the required gun elevation rate data.

Since the control in azimuth is exactly identical to that described for elevation, further description of the azimuth control is not thought necessary. The apparatus involved in the azimuth control are given the same reference numbersasthe corresponding apparatus inthe'elevation control but areprimed.

Theslip friction connections I59;v 6!! are pro videdso that the displacement control of the gun from the main handle I is not interfered with by the automatic rate control just described. Should handle I be additionally displaced-in elevation, for example, whilethe rate control is in operation, shaft 6 and gun I00 will continue' t'o' rotate at the rate introduced-by the 'ratehand Wheel5I- as-soon as handle I is released, but will have been additionally displaced by the additional displacement of handle I. The additional displacement of shaft 6 will have no effect on the rate of rotation of shaft H0, since it is impossible for Worm drive 59 to operate in the reverse direction and therefore, friction clutch 60 will simply slip. Thus, whenever the operator forces a rotation of the gun through handle I at a rate which does not correspond to that of the rate control, slippage of clutch 60 will occur.

There is thus provided by the present invention a type of control wherein the operator may either position the guns at any desired orientation through handle I, or he may set up a continuous rate of rotation of said gun at an adjustable rate by imparting a corresponding rate to the rate handwheel. Moreover he may employ these two types of control simultaneously, each acting independently of the other, thus facilitating tracking of the target and increasing the accuracy of the operation.

In another and perhaps more common type of fire control system than the disturbed gunsight' type in which the invention has herein been: illustrated as employed, the operator, instead ofcontrolling the orientation of the gun, rather directly maintains an optical sighting device on the target through his controls. In such'systemsl the computing mechanism requires input data corresponding to the orientation of the sighting device in elevation and azimuth, ,and the e1evation and azimuth rate of rotation of said sight. From these data and from other data, the com-' puter then solves for the lead angle whichlit adds-to the angular orientation of the sight as: vice to obtain the angular orientation of the'gu n required to effect a hit on' the target; It will be obvious" that the tracking control device of the present invention is just as applicable for use in such a fire control systemfas' in the'system in which it hasherein been employed, In" such a case, gun Ififl would be replaced by a suitable sighting device, the orientation of which could then be controlled by the tracking control device of the present invention in' themanniei" previously described. 7

Since'many changes could be made in: the above construction andmany apparently widely different embodimentsof this invention couldbernade without departing from the scope thereof, it is" intended that all matter contained in'the above description or shown in the accompanyingdraw ing shall be interpreted a illustrative and not in' a limiting sense:

What is claimed is:

1. Ina tracking arrangement for a gun provided with a pair of movable shafts for adjusting the position of the'gun, the improvementin themeans' for each variable speed drive having one input" connected to the associated variable" speed, drive output, a handwheel connected'to a'fse'cond'input of each differential, an output shaft-for eachid a ferentialconnect'ed to the adjustable member of the associated variable speed drive,- wherbyi the rate of adjustment of the respective hatidy/"heels controls'the angular turning'rate of the gun, and

means providing a constant brake load on the output shafts of the differentials.

2. In a tracking arrangement for a gun provided with a pair of movable shafts for adjusting the position of the gun, the improvement which comprises means for continuously adjusting the angular position of the gun to correspond to the changing position of a moving target which comprises a variable speed drive for each shaft having a disc driven at constant speed, an adjustable ball carriage and an output cylinder, means con- -necting the cylinders to drive the associated shafts, a differential for each variable speed drive having one input driven by the associated variable speed drive cylinder, a handwheel for each differential connected to a second input thereof, an output shaft for each differential effective to displace the variable ball carriage of the associated variable speed drive whereby the rate of adjustment of the respective handwheels controls the angular turning rate of the gun, and braking means for the output shafts of the differentials to prevent displacement thereof except under control of the handwheels.

3. In a tracking arrangement for a gun provided with a pair of movable shafts for adjusting the position of the gun, the improvement in the means for continuously adjusting the position of the shafts to move the gun according to the changing relative position of a target which comprises a variable speed drive for each shaft, said drives having variable speed outputs frictionally connected to the gun adjusting shafts and having rate members adjustable for controlling the speed of the outputs, a constant speed source of power for the variable speed drives, a differential for each variable speed drive having one input connected to the associated variable speed drive output, a handwheel connected to a second input of each differential, an output shaft for each differential connected to the adjustable member of the associated variable speed drive whereby the rate of adjustment of the respective handwheels controls the angular turning rate of the gun, braking means on the output shafts of the differentials to prevent displacement of the adjustable members except under control of the handwheels, and adjustment means connected to the gun adjusting shafts for displacing the shafts relative to the outputs of the variable speed drives by slipping the frictional connection.

4. A tracking device for controlling the movement of an object, comprising a variable speed drive having a power actuated constant speed input, a variable speed output and a rate member adjustable to control the speed of the output, a

differential having three operably related members, means operably connecting the output of the variable speed drive to one member of the differential, a movable control member connected to position the second member of the diiferential, means operably connecting the third member of the differential .to the rate member of the variable speed drive, means connecting the output of the variable speed drive to move the object in accordance with the rate of movement of said output, and means providing a brake load on the means connecting the third member of the differential to the rate member, whereby, upon release of the control member after being moved at the desired rate, the driven object. is maintained at the said rate.

5. A tracking device for controlling the movement of an object, comp-rising a variable speed drive having a power actuated constant speed input, a variabl speed output and a rate mem- 'ber adjustable to control the speed of the output, a differential having three operably related members, means operably connecting the output of the variable speed drive to one member of the differential, a movable control member connected to position the second member of the differential, means operably connecting the third member of th differential to the rate member of the variable speed drive, slippable means connecting the output of the variable speed drive to move the object in accordance with the rate of movement thereof, adjusting means connected for adjusting the object by overcoming the slippable means, and means providing a brake load on the means connecting the third, member of the differential to the rate member.

EARL W. CHAFEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,206,875 Chafee et al July 9, 1940 1,951,875 Laabs Mar. 20, 1934 2,029,094 DeVlieg et a1 Jan. 28, 1936 2,262,330 MacNeil et al Nov. 11, 1941 2,340,865 Chafee et al. 1 Feb. 8, 1944 1,849,611 Busser Mar. 15, 1932 2,004,067 Watson June 4, 1935 FOREIGN PATENTS Number Country Date 371,517 Great Britain Apr, 28, 1932 Certificate of Correction Patent No. 2,426,597. September 2, 1947. EARL W. CHAFEE It is hereby certified that the above numbered patent was erroneously issued to the inventor, said Chafee, whereas said patent should have issued to Sperry Gyroscope Company, Inc., of Brooklyn, New York, a corporation of New York, as assignee of the entire interest therein, as shown by the record of assignments in this Oflice; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the ease in the Patent Ofiioe. Signed and sealed this 4th day of November, A. D. 1947.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,426,597. September 2, 1947. EARL W. CHAFEE It is hereby certified that the above numbered patent'was erroneously issued to the inventor, said Chafee, whereas said patent should have issued to Sperry Gyroscope Company, Inc., of Brooklyn, New York, a corporation of New York, as assignee of the entire interest therein, as shown by the record of assignments in this Office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 4th day of November, A. D. 1947.

THOMAS F. MURPHY,

Assistant Gammissz'oner of Patents. 

